1. Field of the Invention
The present invention relates to chain wheels, and more particularly, to a chain wheel assembly and a chain wheel device using it, which is installed on a wheel hub of a back wheel of a bicycle.
2. Description of the Related Art
A conventional wheel hub of a back wheel of a bicycle is provided with plural chain wheels with different diameter sizes, which are optionally engaged by a chain through a derailleur, whereby chain wheels with multiple gear ratios are applied on the bicycle.
DE102012006771.2 discloses a pinion assembly 12, which is provided with plural chain wheels 141 to 1410 with different diameters and numbers of sprockets, wherein the chain wheel 1410 with the largest diameter engages one end of an impeller 16, and other chain wheels 141 to 146 with smaller diameters engage the positions where an outer thread 22 being screwed by an inner thread 30 and the position where the impeller 16 is axially positioned at.
However, as shown by the drawings of DE102012006771.2, the chain wheels 141 to 1410 are integrally formed. Compared with other chain wheels formed by plural single-piece board materials, cost of manufacturing is high; furthermore, such a component lacks the advantage of being lightweight.